GLUT Objects

The focus of this assignment is building graphical objects out of higher-level components than vertices and polygons. There are two pieces of it: the clown and a library function.

The Clown

Build a scene that looks like the following "clown." You can run this program on any of the Linux machines except Puma.

~cs307/public_html/assignments/clown

• Each object should be a different color, so that all the edges are plainly visible.
• You must use RGB color for at least two objects
• The bounding box must be correct, so that I can see the whole clown by using the mouse.
• Mark the origin using a magenta dot, as in the model.
• It's important that the clown's hat is tilted as it is. I don't want the hat's axis to lie in any of the major planes (xz, yz or xy).

The goal of this assignment is to work with the affine transformations of translation, rotation and scale, and also the matrix stack. Ideally, I'd like to see you work with different embedded frames (a frame is a coordinate system: axes plus an origin). I'll leave you to decide what frames are useful, but it will help to think modularly.

Try to avoid magic constants for positioning, angles, scaling, and so forth (meaning unlabeled, undocumented numbers directly in the modeling code). Some of these are inevitable, of course, but there are connections among them, too. The positioning of the hand is related to the length of the arm, for example. The positioning of the pom-pom is related to the positioning and dimensions of the hat. Try to make these relationships clear in your code.

Also, try to make your clown flexible. For example, suppose your boss at Pixar says that the head needs be bigger, flatter, wider, or whatever: what needs to be changed in your code? Try to make it easy to adjust things like this, either by coding or documentation.

Please read the standard instructions for all assignments

Library Functions

Look through the graphical objects that have been contributed to our 307 library by former students. You can find these in the following directories:

~cs307/pub/tw/f05/
~cs307/pub/tw/f06/
~cs307/pub/tw/f07/

(This course wasn't taught last fall, which is why there is no f08 directory.)

Each person contributed some source code as a .cpp file. She also contributed a demo version of her object, so that you can run the file to see what the object looks like. The source code for that is a .cc file, and the executable demo program has no extension.

For example, if Jackie Shaw contributed a guitar, she submitted the following files:

    ~cs307/pub/tw/f07/jshaw.cpp
    ~cs307/pub/tw/f07/jshaw_guitar.cc
    ~cs307/pub/tw/f07/jshaw_guitar
  

where the first is the code for a guitar, the second calls the code defined in the first, and the third is an actually runnable file.

What you must do:

• Check 'em out! Run the demos so that you can see what your predecessors have contributed.
• Choose one to port to Python. Compare Justine Aylmer's source code files to the port of her code in pytw/jaylmer.py. (You can see one advantage of Python in that we only have to worry about one file, not three or more). Another example is pytw/wwellesl.py, though that one was written from scratch, rather than ported from C.
• I suggest that once you've chosen an object to port, post to the conference to claim the object(s). That way, no one will duplicate anyone else's work.
• Improve the documentation. Many students gave some description of the origin and bounding box of their object, but these vary in quality. Experiment with the code so that the description is clear and explicit, as with pytw/wwellesl.py.

This effort will give us all a lot of cool stuff to work with, and will make them easier to work with.

You will probably find that you don't need to dig into the code in order to port it. You'll have to change the syntax a little (such as function definitions) and re-code control structures like if and for. If you run into something that you're not sure how to port, please ask. This part of the assignment isn't supposed to be difficult.

When you're done, you'll be able to copy it to ~cs307/pub/pytw/ which will then be available for everyone. In the Creative Scene assignment, you'll make your own contribution as well.

Revisions and Clarifications

In doing your porting, you mostly just need to convert the C code to Python code, but I'd also like you to do the following:

• Put a nice comment at the top of the file, describing it, and giving credit to the original author. Your top-of-file comment should include your own name, crediting yourself with porting it, and a copyright notice. (You may not know the copyright status of the original, but by thinking about this now, you'll be prepared to think about the copyright status of your own contribution.) I've modeled this with the pytw/jaylmer.py file.
• Convert the documentation for each function to the Python style, using a triple-quoted string as the first element of the definition of the function. (See Python Docstring Conventions for more than you ever wanted to know about documentation strings in Python.) Do the following to see the effect:

  pydoc jaylmer
  

• Combine multiple objects into a single file, when it's sensible to do that. I've combined Justine's three objects into a single file, here.

Math

Please do the problems in this PDF file: math2.pdf

Written by Scott D. Anderson
scott.anderson@acm.org

This work is licensed under a Creative Commons License.